runtime: pass setmg function to cgo_init
This keeps the logic about how to set the thread-local variables
m and g in code compiled and linked by the gc toolchain,
an important property for upcoming cgo changes.
It's also just a nice cleanup: one less place to update when
these details change.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7560048
diff --git a/src/pkg/runtime/cgo/gcc_openbsd_amd64.c b/src/pkg/runtime/cgo/gcc_openbsd_amd64.c
index e9cc818..5a5a171 100644
--- a/src/pkg/runtime/cgo/gcc_openbsd_amd64.c
+++ b/src/pkg/runtime/cgo/gcc_openbsd_amd64.c
@@ -11,6 +11,7 @@
#include "libcgo.h"
static void* threadentry(void*);
+static void (*setmg_gcc)(void*, void*);
// TCB_SIZE is sizeof(struct thread_control_block),
// as defined in /usr/src/lib/librthread/tcb.h
@@ -82,12 +83,13 @@
}
void
-x_cgo_init(G *g)
+x_cgo_init(G *g, void (*setmg)(void*, void*))
{
pthread_attr_t attr;
size_t size;
void *handle;
+ setmg_gcc = setmg;
pthread_attr_init(&attr);
pthread_attr_getstacksize(&attr, &size);
g->stackguard = (uintptr)&attr - size + 4096;
@@ -155,15 +157,10 @@
ts.g->stackguard = (uintptr)&ts - ts.g->stackguard + 4096;
/*
- * Set specific keys. On OpenBSD/ELF, the thread local storage
- * is just before %fs:0. Our dynamic 6.out's reserve 16 bytes
- * for the two words g and m at %fs:-16 and %fs:-8.
+ * Set specific keys.
*/
- asm volatile (
- "movq %0, %%fs:-16\n" // MOVL g, -16(FS)
- "movq %1, %%fs:-8\n" // MOVL m, -8(FS)
- :: "r"(ts.g), "r"(ts.m)
- );
+ setmg_gcc((void*)ts.m, (void*)ts.g);
+
crosscall_amd64(ts.fn);
return nil;
}
